What are antiphospholipid antibodies?

Lupus Foundation of America

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Antiphospholipid antibodies cause blood vessels to become narrow and irregular (vasculopathy), which then causes blood clots to form (thrombosis). This can lead to complications such as stroke, heart attack, and miscarriage.

There are several kinds of antiphospholipid antibodies. The three most widely measured are:
  • Lupus anticoagulant
  • Anticardiolipin antibody 
  • Anti-β2 glycoprotein 

 These antibodies are closely related, but are not the same. This means that a person can have one, and not the others. They are closely related since they are all directed against phospholipid molecules, a type of fat molecule that is part of the normal cell membrane.

These antibodies were first discovered in people who have lupus, but it is not necessary to have lupus to have these antibodies. In fact, in most studies, more than 50 percent of people with these antibodies do not have lupus. We do not yet understand why a person’s immune system begins to manufacture antiphospholipid antibodies.

Dr. Michelle Petri

is the Director of the Hopkins Lupus Cohort, a longitudinal study of morbidity and mortality in systemic lupus erythematosus, and Co-Director of the Hopkins Lupus Pregnancy Center.

Medically reviewed on